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Wednesday, May 23, 2012

Bacterial Endospre

Certain bacteria can form endospores in dry
environments in a process called sporulation. They are called endospores
because the spores form within the cell. Endospores offer great advantages to
bacterial cells because they are extremely resistant to a number of harsh
environments, including: heat, desiccation, radiation, chemicals, acids, and
drying. The discovery of bacterial endospores was important to microbiology
because it provided knowledge on proper methods for sterilization of culture
media, foods, and other perishable items. Many organisms form spores, but the
bacterial endospore is unique in its heatresistance capabilities. Endosporesare bacterial structures (resting
cells) formed by a few groups of bacteria as intracellular structures, but
ultimately they are released as free endospores. Biologically, endospores are a
fascinating type of cell. Endospores exhibit no signs of life, being described
as cryptobiotic. They are highly resistant to environmental stresses such as
high temperature (some endospores can be boiled for hours and retain their
viability), irradiation, strong acids, disinfectants, etc. They are thought to
be the most durable cell produced in nature. Although cryptobiotic, they retain
viability indefinitely, such that under appropriate environmental conditions,
they germinate back into vegetative cells. The primary function of
most endospores is to ensure the survival of a bacterium through periods of
environmental stress.

They are therefore
resistant to ultraviolet and gamma radiation, desiccation, lysozyme,
temperature, starvation, and chemical disinfectants.

Endospores are commonly
found in soil and water, where they may survive for long period. An endospore
is a dormant, tough, non-reproductive structure produced by a small number of
bacteria from the Firmicute family. Endospores are formed mainly by two genera of Gram-positive bacteria:Bacillus,the aerobic sporeformers,
andClostridium,the anaerobic sporeformers. Both
genera contain pathogens, and the endospores produced by these bacteria
invariably play some role in the toxicity, transmission or survival of the
pathogen.